scholarly journals Multi-Scale Structural and Tensile Mechanical Response of Annulus Fibrosus to Osmotic Loading

2012 ◽  
Author(s):  
Woojin M. Han ◽  
Nandan L. Nerurkar ◽  
Lachlan J. Smith ◽  
Nathan T. Jacobs ◽  
Robert L. Mauck ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Intervertebral Disc ◽  
Mechanical Testing ◽  
Biochemical Composition ◽  
Annulus Fibrosus ◽  
Mechanical Response ◽  
Tissue Level ◽  
Multi Scale ◽  
Osmotic Loading

The annulus fibrosus (AF) is a multi-lamellar fibrocartilagenous ring in the intervertebral disc. The variation of biochemical composition from the outer to the inner AF is largely responsible for the heterogeneous mechanical properties. In vitro tissue-level studies require mechanical testing in aqueous buffers to avoid tissue dehydration. The varying glycosaminoglycan (GAG) contents from outer to inner AF suggest that the response to high and low PBS osmolarity may also be different with radial position. Previous studies in tendon and ligament have been conflicting: soaking tendon fascicles in PBS decreased tensile modulus1 and treating ligament in buffer had no effect on modulus.2

EXPERIMENTAL METHODS FOR THE BIOMECHANICAL INVESTIGATION OF THE HUMAN SPINE: A REVIEW

2014 ◽  
Vol 14 (01) ◽  
pp. 1430002 ◽  
Author(s):  
NICOLA BRANDOLINI ◽  
LUCA CRISTOFOLINI ◽  
MARCO VICECONTI
Keyword(s):  
Mechanical Properties ◽  
Numerical Modeling ◽  
Mechanical Testing ◽  
Structural Properties ◽  
Vertebral Body ◽  
Reference Frames ◽  
Tissue Level ◽  
Whole Body ◽  
Human Spine

In vitro mechanical testing of spinal specimens is extremely important to better understand the biomechanics of the healthy and diseased spine, fracture, and to test/optimize surgical treatment. While spinal testing has extensively been carried out in the past four decades, testing methods are quite diverse. This paper aims to provide a critical overview of the in vitro methods for mechanical testing the human spine at different scales. Specimens of different type are used, according to the aim of the study: spine segments (two or more adjacent vertebrae) are used both to investigate the spine kinematics, and the mechanical properties of the spine components (vertebrae, ligaments, discs); single vertebrae (whole vertebra, isolated vertebral body, or vertebral body without endplates) are used to investigate the structural properties of the vertebra itself; core specimens are extracted to test the mechanical properties of the trabecular bone at the tissue-level; mechanical properties of spine soft tissue (discs, ligaments, spinal cord) are measured on isolated elements, or on tissue specimens. Identification of consistent reference frames is still a debated issue. Testing conditions feature different pre-conditioning and loading rates, depending on the simulated action. Tissue specimen preservation is a very critical issue, affecting test results. Animal models are often used as a surrogate. However, because of different structure and anatomy, extreme caution is required when extrapolating to the human spine. In vitro loading conditions should be based on reliable in vivo data. Because of the high complexity of the spine, such information (either through instrumented implants or through numerical modeling) is currently unsatisfactory. Because of the increasing ability of computational models in predicting biomechanical properties of musculoskeletal structures, a synergy is possible (and desirable) between in vitro experiments and numerical modeling. Future perspectives in spine testing include integration of mechanical and structural properties at different dimensional scales (from the whole-body-level down to the tissue-level) so that organ-level models (which are used to predict the most relevant phenomena such as fracture) include information from all dimensional scales.

scholarly journals Multi-scale Structural and Tensile Mechanical Response of Annulus Fibrosus to Osmotic Loading

2012 ◽  
Vol 40 (7) ◽  
pp. 1610-1621 ◽  
Author(s):  
Woojin M. Han ◽  
Nandan L. Nerurkar ◽  
Lachlan J. Smith ◽  
Nathan T. Jacobs ◽  
Robert L. Mauck ◽  
...  
Keyword(s):  
Annulus Fibrosus ◽  
Mechanical Response ◽  
Multi Scale ◽  
Osmotic Loading

Osmo-inelastic response of the intervertebral disc annulus fibrosus tissue

2020 ◽  
Vol 234 (9) ◽  
pp. 1000-1010
Author(s):  
Amil Derrouiche ◽  
Ameni Zaouali ◽  
Fahmi Zaïri ◽  
Jewan Ismail ◽  
Zhengwei Qu ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Annulus Fibrosus ◽  
Mechanical Response ◽  
Rate Sensitivity ◽  
Image Correlation ◽  
Inelastic Response ◽  
Full Field ◽  
Osmotic Effect ◽  
Rate Dependent ◽  
Optical Strain

The aim of this article is to provide some insights on the osmo-inelastic response under stretching of annulus fibrosus of the intervertebral disc. Circumferentially oriented specimens of square cross section, extracted from different regions of bovine cervical discs (ventral-lateral and dorsal-lateral), are tested under different strain-rates and saline concentrations within normal range of strains. An accurate optical strain measuring technique, based upon digital image correlation, is used in order to determine the full-field displacements in the lamellae and fibers planes of the layered soft tissue. Annulus stress–stretch relationships are measured along with full-field transversal strains in the two planes. The mechanical response is found hysteretic, rate-dependent and osmolarity-dependent with a Poisson’s ratio higher than 0.5 in the fibers plane and negative (auxeticity) in the lamellae plane. While the stiffness presents a regional-dependency due to variations in collagen fibers content/orientation, the strain-rate sensitivity of the response is found independent on the region. A significant osmotic effect is found on both the auxetic response in the lamellae plane and the stiffness rate-sensitivity. These local experimental observations will result in more accurate chemo-mechanical modeling of the disc annulus and a clearer multi-scale understanding of the disc intervertebral function.

In vitro comparison between mechanical properties and elastographic characterization of porcine intervertebral disc

2015 ◽  
Vol 18 (sup1) ◽  
pp. 1906-1907
Author(s):  
Y. Chotar-Vasseur ◽  
T. Cachon ◽  
B. Ponsard ◽  
C. Carozzo ◽  
E. Viguier
Keyword(s):  
Mechanical Properties ◽  
Intervertebral Disc ◽  
In Vitro Comparison

Intra- and Extrafibrillar Fluid Exchange in the Disc

2007 ◽  
Author(s):  
Y. Schroeder ◽  
S. Sivan ◽  
W. Wilson ◽  
J. M. Huyghe ◽  
A. Maroudas ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Intervertebral Disc ◽  
Water Content ◽  
Biochemical Composition ◽  
Mechanical Load ◽  
Crack Opening ◽  
Cellular Responses ◽  
Fluid Exchange ◽  
External Mechanical Load

The mechanical properties of the intervertebral disc are regulated by its biochemical composition. With ageing and degeneration the water content of the disc decreases which highly influences the mechanical properties. The disc is subjected to a combination of elastic, viscous and osmotic forces. Osmotic forces are shown to have a major impact on crack opening and propagation [1] and on cellular responses [2]. In particular, osmosis provides an understanding on why fissures in the degenerating disc are so poorly related to external mechanical load [3].

Understanding and Regulating Cell-Matrix Interactions Using Hydrogels of Designable Mechanical Properties

2021 ◽  
Vol 17 (2) ◽  
pp. 149-168
Author(s):  
Jiapeng Yang ◽  
Yu Zhang ◽  
Meng Qin ◽  
Wei Cheng ◽  
Wei Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Research Direction ◽  
Mechanical Environment ◽  
Cell Functions ◽  
Cell Matrix ◽  
Matrix Interactions ◽  
Sense And Respond ◽  
Cell Matrix Interactions

Similar to natural tissues, hydrogels contain abundant water, so they are considered as promising biomaterials for studying the influence of the mechanical properties of extracellular matrices (ECM) on various cell functions. In recent years, the growing research on cellular mechanical response has revealed that many cell functions, including cell spreading, migration, tumorigenesis and differentiation, are related to the mechanical properties of ECM. Therefore, how cells sense and respond to the extracellular mechanical environment has gained considerable attention. In these studies, hydrogels are widely used as the in vitro model system. Hydrogels of tunable stiffness, viscoelasticity, degradability, plasticity, and dynamical properties have been engineered to reveal how cells respond to specific mechanical features. In this review, we summarize recent process in this research direction and specifically focus on the influence of the mechanical properties of the ECM on cell functions, how cells sense and respond to the extracellular mechanical environment, and approaches to adjusting the stiffness of hydrogels.

scholarly journals The effects of glucosamine sulfate on intervertebral disc annulus fibrosus cells in vitro

2015 ◽  
Vol 15 (6) ◽  
pp. 1339-1346 ◽  
Author(s):  
Gwendolyn A. Sowa ◽  
J. Paulo Coelho ◽  
Lloydine J. Jacobs ◽  
Kasey Komperda ◽  
Nora Sherry ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Annulus Fibrosus ◽  
Glucosamine Sulfate

Corrigendum to: Elastic properties of the forisome

2007 ◽  
Vol 34 (11) ◽  
pp. 1053
Author(s):  
Stephen A. Warmann ◽  
William F. Pickard ◽  
Amy Q. Shen
Keyword(s):  
Mechanical Properties ◽  
Radial Direction ◽  
Mechanical Response ◽  
Viscoelastic Model ◽  
Strain Curve ◽  
Longitudinal Direction ◽  
Tensile Tests ◽  
Before And After

Forisomes are elongate Ca2+-responsive contractile protein bodies and act as flow blocking gates within the phloem of legumes. Because an understanding of their mechanical properties in vitro underpins understanding of their physiology in vivo, we undertook, using a microcantilever method, microscopic tensile tests (incremental stress-relaxation measurements) on forisomes from Canavalia gladiata (Jacq.) DC Akanata Mame and Vicia faba L. Witkiem Major. Viscoelastic properties of forisomes in their longitudinal direction were investigated before and after Ca2+-induced contraction, but in the radial direction only before contraction. Forisomes showed mechanical properties typical of a biological material with a unidirectional fibrous structure, i.e. the modulus of elasticity in the direction of their fibers is much greater than in the radial direction. Creep data were collected in all tensile tests and fit with a three parameter viscoelastic model. The pre-contraction longitudinal elastic moduli of the forisomes were not differentiable between the two species (V. faba, 660���360�kPa; C. gladiata, 600���360�kPa). Both species showed a direction-dependent mechanical response: the elastic modulus was dramatically smaller in the radial direction than in the longitudinal direction, suggesting a weak protein cross-linking amongst longitudinal protein fibers. Activation of forisomes decreased forisome stiffness longitudinally, as evidenced by the loss of toe-region in the stress strain curve, suggesting that the forisome may have dispersed or disordered its protein structure in a controlled fashion. Contractile forces generated by single forisomes undergoing activation were also measured for V. faba (510���390�nN) and C. gladiata (570���310�nN).

Digital Image Correlation Method in Measuring the Out of Plane Displacement: A Case Study on an Artificial Intervertebral Disc

2020 ◽  
Author(s):  
Hassan M. Raheem ◽  
Willie “Skip” E. Rochefort ◽  
Brian K. Bay
Keyword(s):  
Digital Image Correlation ◽  
Intervertebral Disc ◽  
Digital Image ◽  
Annulus Fibrosus ◽  
Mechanical Response ◽  
Spinal Column ◽  
Correlation Method ◽  
Image Correlation ◽  
Therapeutic Interventions ◽  
Compression Tests

Abstract We have developed a simple, low-cost, and innovative design — known as a “disc emulator” to mimic the mechanical response of a motion segment (vertebra - intervertebral disc-vertebra) of the human spinal column under axial compression loads. The disc emulator consists of upper and lower components that mimic the human vertebrae and a middle component that represents the annulus fibrosus (AF). This study aims to investigate the effects of changing the stiffness of artificial annulus fibrosus of the disc emulator on the bulging measurements while performing compression tests on the disc emulator. A non-contact measurement — digital image correlation (DIC) — was used for the bulging measurements. The results show that the bulging at the posterior region for the discs without nucleus pulposus (NP) bulged inwards, but the bulging at the posterolateral region was outwards, which accords with the reported behavior of the human disc, for the disc without and with NP regardless of the stiffness of the discs. Changing the stiffness of the artificial annulus fibrosus (AAF) alters the bulging magnitudes in the disc, which shows similar responses with respect to the available data on the human disc. The emulator provides a convenient experimental platform for evaluating normal and pathological disc states and assessing the biomechanics of potential therapeutic interventions.

Finite Element Modeling of Entangled Collagen Fiber Gels With Randomly Oriented Fibers

2009 ◽  
Author(s):  
Xiaoyue Ma ◽  
J. Edward Green ◽  
Keith J. Gooch ◽  
Rebecca M. Jansen ◽  
Richard T. Hart
Keyword(s):  
Mechanical Response ◽  
Biological Tissues ◽  
Structural Protein ◽  
Satisfactory Description ◽  
Fibrin Gels ◽  
Multi Scale ◽  
Multiple Length Scales ◽  
Extracellular Matrix Components ◽  
Underlying Network

Collagen is an important structural protein in the human body, and its molecules form structural aggregates at multiple length scales (i.e., microfibrils, fibrils, fibers, and bundles of different sizes) in biological tissues and organs [1]. The mechanical properties of most tissues are dependent on the underlying network of collagen fibers, proteoglycans, and other extracellular matrix components [2]. Similarly, the properties of in vitro tissue analogs, often created from collagen or fibrin gels, are also dependent on the organization of the biopolymers [3]. The overall mechanical response is intrinsically multi-scale and dynamic in both materials. As a result, a satisfactory description of the microstructure is important for exploring the essential physics of the tissue.

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